1) Lee Sin (I love jungling with this guy, definately my top favorite, so much fun right there)
2) Akali (When i wan't to win 95% chance)
3) Ezreal (Favorite AD carry, those snipes feels so awesome)
4) Ryze (His combo feels pretty good to throw at your enemies, also he is very often underrestimated)
5) Darius (When i wan't be sure to have fun)

Rengar seems awesome, and picking up Swain now aswell... Both seem very fun to me...